The invention relates to catalysts and to a method of use of catalysts in catalytic gas phase reactions.
Catalysis is a surface phenomenon and many catalytic materials are expensive (e.g. Platinum, Palladium). It is known to deposit the catalytic material upon a supporting substrate, which may be a porous body or a powder, with the object of obtaining a large exposed surface area from a given volume of the catalytic material.
Techniques generally used to deposit the catalytic material are vapour deposition, for example by decomposition of a gas passed over or through the substrate, or deposition of the catalytic material from a solution in which the substrate is immersed.
A problem faced in the manufacture of catalysts in particular for catalytic gas phase reactions is the durability or life of the catalyst when exposed to the severe environment and high temperature typical of many such reactions. The need for a large exposed surface area of substrate support conflicts with the durability requirement, since high surface area porous substrates are unstable at high temperatures and tend to sinter with consequent reduction in surface area and loss of catalytic activity.
We are aware that cathode sputtering of platinum onto a particulate substrate has been proposed for manufacturing a fluid electrode of high catalytic surface area.